A once-in-a-decade surge in U.S. oil inventories had traders scratching their heads this week. U.S. crude-oil supplies rose by 10 million barrels last week, the biggest one-week gain since 2001, according to the U.S. Energy Information Administration. But much of the increase happened on the West Coast, far from the gushing wells in North Dakota and Texas. ClipperData, which tracks oil imports, says the massive jump in oil stockpiles comes down to a big coincidence. Four tankers delivered Colombian crude to West Coast refineries last week, leading to a 1.5-million-barrel boost in Colombian exports to the region, which stretches from Arizona to Alaska, according to ClipperData. “I think it’s an anomaly week, which is not unusual on the west coast,” said Abudi Zein, ClipperData’s chief operating officer. “It’s a very volatile region in terms of imports.” ClipperData tracks U.S. oil and petroleum-product imports and domestic shipments using […]